I would check with the caliper manufacturer, however 3/4 bore master seems small for the two front calipers. I typically recommend 3/4 bores for clutch only. Looking at the last few posts on clutch issues, it's beginning to look like 3/4 is too small for some of them also.
Simply put, if the master cylinder does not have enough volume,(more than the volume of both of the calipers) it will not fully engage the calipers.
This is the second post today I have replied to with this suspected "volume" problem. Best of luck and hope this helps. Check the link below, same issue, just with a clutch master cylinder.
https://lateral-g.net/forums/showthread.php4?t=40386